The advantages provided by underground pipes are well recognized by people in the various industries, such as telecommunication, oil, water and gas. However, the laying of underground pipes can be expensive and time consuming. This is especially the case when the terrain provides substantial landscape obstacles such as undulating ground and rivers, in addition, the client requires the pipes to be buried deep into the ground.
The development of the plough system (known in the industry as the “SpiderPlow, Foeck Plough or Spider Plough”) has revolutionized the laying of underground pipe. The plough system consists of a winch vehicle which is attached via a cable to a plough vehicle. The plough system can lay polyethylene pipe very quick in a variety of terrain.
When a pipeline is laid, the outer diameter of the pipe generally does not change. However, the internal diameter of the pipe often changes to increase or decrease the wall thickness of the pipe. The increase in wall thickness of the pipe is usually required when the pipe is likely to encounter increased forces such as when it is located under a road or watercourse.
Polyethylene pipes that are laid using a plough vehicle are often joined using a fast fusion welding machine. Polyethylene pipe that is joined through fusion welding normally creates a butt joint. A butt joint is formed by holding the two sections of pipe rigidly using a two pairs of jaws which form part of the fusion welding machine. The two ends of the pipes are faced to square the ends of the pipes and prepare the pipes for welding. The ends of the pipes are then heated above their melting point using a heating element. The pipes are then pushed together using the jaws which forces the two melted faces of the respective pipes together to fuse into each other and hence form the butt joint.
Fusion welding usually creates a joint that is as strong as or stronger than the parent material and is very reliable when used on pipes that have the same wall thickness. However, fusion welding does not work well with pipes that have different wall thickness. Therefore, when two pipes of a different wall thickness needs to be joined together, a prefabricated, transition section of pipe is often used. The transition section of pipe has two ends of different wall thickness which reflect the wall thickness of each of the pipes that the transition section of pipe is to be joined.
An transition section of pipe is undesirable as the transition section must be preordered and premade and must be ready on-site when needed. Further, the fusion welding of this transition section is time consuming and cumbersome due to the number of welds required.
The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.